72V BATTERY PACK REPAIR AND SAFETY

DrPandaPHD

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Back-story:

Today I turned on my enduro-style ebike to a terrible sight: it didn't turn on. "Ok, it's just dead" I thought until plugging it into the charger and the light stayed green... "oh no." I left it plugged in while I went inside and started research.it didn't take long for me to realize that having it plugged in in this state might not be the safest idea. I went out and unplugged it, removed it from the bike and tested voltages. At this point the battery was outputting 19.4v; this was not a good sign considering this is a 72v 48ah pack.

My thoughts:
The bike has not been used in 2-4 months and has just been stored in my garage. There is a factory-installed 12v dc-dc converter that is always on supplying the horn, lights, and alarm. My assumption is that it was stored with a low charge as I didn't expect to go so long without using it and over the last few months this small draw completely drained the battery. I'm now debating disassembling the battery to test cell voltages and see how many(if any) are still usable.

My question(s):
With all this info, what steps should I take to safely work on this battery. I know 72v is a fairly dangerous voltage to work with and I don't want to do anything dum dum and get myself a big ol' medical or funeral bill.

Is there a possibility that the battery is in some sort of bms initiated "sleep" mode and can therefore be revived?

I will attach images of the battery so you can see what I am seeing.
 

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Back-story:

Today I turned on my enduro-style ebike to a terrible sight: it didn't turn on. "Ok, it's just dead" I thought until plugging it into the charger and the light stayed green... "oh no." I left it plugged in while I went inside and started research.it didn't take long for me to realize that having it plugged in in this state might not be the safest idea. I went out and unplugged it, removed it from the bike and tested voltages. At this point the battery was outputting 19.4v; this was not a good sign considering this is a 72v 48ah pack.

My thoughts:
The bike has not been used in 2-4 months and has just been stored in my garage. There is a factory-installed 12v dc-dc converter that is always on supplying the horn, lights, and alarm. My assumption is that it was stored with a low charge as I didn't expect to go so long without using it and over the last few months this small draw completely drained the battery. I'm now debating disassembling the battery to test cell voltages and see how many(if any) are still usable.

My question(s):
With all this info, what steps should I take to safely work on this battery. I know 72v is a fairly dangerous voltage to work with and I don't want to do anything dum dum and get myself a big ol' medical or funeral bill.

Is there a possibility that the battery is in some sort of bms initiated "sleep" mode and can therefore be revived?

I will attach images of the battery so you can see what I am seeing.
In a nutshell, go to Cellsaviors.com for the whole 411. You'll probably have to disassemble the whole pack & test each cell with a B6AC or equivalent.
There is a way to wake up the bms, again cellsaviors can show you how.
Their companion site is Batteryhookup.com - check it out - you'll like, I guarantee!
 
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